French patent application 2 632 593 of the applicant describes an apparatus comprising a ventilator which blows cold or hot air into a conduit extending along the lower portion of the internal lateral surface of the vehicle. This conduit empties into two air outlet passages, the first being situated against the lateral surface of the conduit adjacent the interior of the vehicle and ensuring a distribution of air downwardly perpendicular to the floor of the vehicle, and the second being located above the conduit against the internal lateral surface of the vehicle and ensuring a distribution of air at the level of the windows. This second air passage is provided, at its base, with an opening adapted to cause air from the vehicle to enter the passage so as to improve the flow rate of the apparatus by convection.
This installation has several drawbacks, particularly as to the distribution of cold or heated air in the direction of the floor.
In the first place, the air passage located in the lower portion of the apparatus and ensuring blowing toward the ground has size problems, because it is juxtaposed to the conduit, and weight problems, the more so because its fragility, particularly as to the impact of traveler's feet, requires providing it with rigidifying members.
On the other hand, this apparatus requires, to effectively direct the air toward the ground, the use of deflector plates. When the blown air is reflected from these plates, its speed decreases and there is a reduction of flow.
Moreover, this flow depends also on the section of the air outlet zone and, as aesthetic considerations often require that the conduit be covered by a covering, this section is reduced by the thickness of this covering, particularly in the case of a pile fabric.
Finally, as this apparatus blows air downwardly perpendicular to the floor, there will be on the one hand a poor distribution of this air, particularly toward the middle of the vehicle and on the other hand a reflection from the floor. This reflection has the result of sending the air back in the direction of the upper part of the conduit and particularly toward the opening which normally receives air at the ambient temperature of the vehicle, which causes a loss of efficiency.